Polymer Electrolyte Membrane, Process For Production Thereof, Polymer Electrolyte, Electrolyte Composition, Membrane-Electrode Assembly, And Fuel Cell

Abstract

The polymer electrolyte membrane of the present invention is constituted of a block copolymer having an ion-conductive block. In the membrane, the ion-conductive block 12 forms ion-conductive domains 14 in a cylindrical shape arranged parallel to the thickness direction d of the polymer electrolyte membrane. The polymer electrolyte membrane has high ion conductivity, and capable of generating high output without humidification by a humidifier or at a low humidity.

1 . A polymer electrolyte membrane comprised of a block copolymer having an ion-conductive block, wherein the ion-conductive block forms ion-conducting cylindrical domains, arranged parallel to the thickness direction of the polymer electrolyte membrane.  
     
     
         2 . The polymer electrolyte membrane according to  claim 1 , wherein the ion-conductive block is composed of a polymer having an ion-exchange group.  
     
     
         3 . The polymer electrolyte membrane according to  claim 1 , wherein the ion-conductive block is contained at a volume fraction ranging from 5% to 30% in the block copolymer.  
     
     
         4 . The polymer electrolyte membrane according to  claim 1  wherein a main chain of the block copolymer does not contain an aromatic ring.  
     
     
         5 . The polymer electrolyte membrane according to  claim 1 , wherein the ion-conductive block has a repeating unit selected from the group of chemical formulas (1) to (3) below:  
       
         
           
           
               
               
           
         
       
       (in the formula, R 1  denotes a hydrogen atom or methyl, and R 2  denotes alkylene or arylene)  
       
         
           
           
               
               
           
         
       
       (in the formula, R 3  denotes alkylene or arylene)  
       
         
           
           
               
               
           
         
       
       (in the formula, R 4  denotes a hydrogen atom or methyl; R 5  and R 8  denote alkylene or arylene; and R 6  and R 7  may be the same or different and denote respectively a hydrogen atom or an organic group of 1-3 carbon atoms).  
     
     
         6 . A polymer electrolyte membrane, comprising a block copolymer comprising an ion-conductive block and a non-ion-conductive block, the ion-conductive block being contained at a volume fraction ranging from 5% to 30%, and the non-ion-conductive block having a polymer chain with crosslinked structure.  
     
     
         7 . The polymer electrolyte membrane according to  claim 6 , wherein the ion-conductive block constitutes ion-conducting cylindrical domains, arranged parallel to thickness direction of the electrolyte membrane.  
     
     
         8 . The polymer electrolyte membrane according to  claim 6 , wherein the main chain of the block copolymer contains no aromatic ring.  
     
     
         9 . A polymer electrolyte, comprising a block copolymer the ion-conductive block being contained at a volume fraction ranging from 5% to 30%, and the non-ion-conductive block having a repeating unit containing at least one crosslinking group.  
     
     
         10 . The polymer electrolyte according to  claim 9 , wherein a main chain of the block copolymer contains no aromatic ring.  
     
     
         11 . An electrolyte composition, comprising 
 (A) a polymer electrolyte comprising a block copolymer, the non-ion-conductive block having a repeating unit having at least one crosslinking group, and the ion-conductive block being contained at a volume fraction ranging from 5% to  30 %, and    (B) a radical-generator.    
     
     
         12 . The electrolyte composition according to  claim 11 , wherein the main chain of the block copolymer contains no aromatic ring.  
     
     
         13 . A process for producing a polymer electrolyte membrane, comprising steps of 
 forming a membrane of a block copolymer comprising an ion-conductive block, and    orienting cylindrical domains formed from the ion-conductive block in the block copolymer membrane, uniaxially parallel to thickness direction of the polymer electrolyte membrane.    
     
     
         14 . The process for producing a polymer electrolyte membrane according to  claim 13 , wherein the process further comprises a step of crosslinking side chains of the non-ion-conductive block of the block copolymer.  
     
     
         15 . The process for producing a polymer electrolyte membrane according to  claim 13 , wherein the cylindrical domains constituted of the ion-conductive block are oriented uniaxially by a heat treatment and external field application.  
     
     
         16 . A membrane-electrode assembly, comprising the polymer electrolyte membrane set forth in  claim 1  and electrodes provided on both faces of the polymer electrolyte membrane.  
     
     
         17 . The membrane-electrode assembly according to  claim 16 , wherein the ion-conducting components in the polymer electrolyte membrane arranged in a direction perpendicular or nearly perpendicular to the electrode face.  
     
     
         18 . A fuel cell, comprising at least the membrane-electrode assembly having the polymer electrolyte membrane set forth in  claim 1 , and a collecting electrode.  
     
     
         19 . The fuel cell according to  claim 18 , wherein the ion-conducting components in the polymer electrolyte membrane are arranged in a direction perpendicular or nearly perpendicular to the electrode face.